Field of the Invention
The invention disclosed herein relates generally to the field of paper handling preparation and more particularly, to a stacking apparatus.
Background of the Invention
Mailpiece stacking devices are known for taking singulated items and forming them into stacks or columns. Stackers are commonly used in conjunction with photocopier machines, printers, facsimile machines, mailing machines, folders, folder/sealers, small envelope inserting devices, mail openers, envelope printers and labelers. In many of these applications, such as mailing machines and envelope printers, an envelope is imprinted with an address and then immediately fed into a stacker. The ink on the envelope is often not dry as the mailpiece enters the stacker. Failure of the ink to dry enables a successive envelope to smear the ink on a previous envelope in the stacker.
In order to obtain the postal rate discounts, the order of the mailpieces that have been presorted and processed by the mail-processing machine in consecutive order needs to be maintained. The removed stack of mailpieces can be manually placed in a mail tray that is sent to the postal service. In this manner, the user can take advantage of lower postal rates that are provided to users who tray envelopes according to predetermined criteria. The predetermined criteria includes the maintaining of mailpieces in the exact order in which they were processed in the mail processing machine. Generally, the predetermined criteria relates to a reduction in the postal service""s handling of the mail from the mailers. The United States Postal Service (xe2x80x9cUSPSxe2x80x9d) offers several levels of discounts to mailers. The level of discount typically is based on the number of criteria met by the mailer. For example, in order to maximize such postage discounts, the USPS requires that high volume mailers presort the mailpieces, apply a ZIP+4 bar code to each mailpiece, and package their mail into trays with each tray tagged in accordance with the Domestic Mail Manual.
The instant invention relates to a method and apparatus for stacking documents, and more particularly to a stacking machine for stacking filled envelopes that may carry ink that has not completely dried on their surfaces. In addition, the method and apparatus help to maintain the order of the mailpieces so that they can conform to a predefined discount criteria that was considered when the mailpieces were being prepared (i.e., addressed, inserted).
Thus, one of the problems of the prior art is that a ink from an envelope can smear onto an adjacent envelope. Another problem of the prior art is degradation of printed images and transference of ink. Another problem is that it is desirable to maintain the order of the mailpieces being stacked. Therefore, a system and method for stacking envelopes is needed which provides decreased smearing and maintains mailpiece order.
This invention overcomes the disadvantages of the prior art by providing an apparatus for stacking mailpieces. A stack of mail pieces rests on top of two elongated intermittently rotating S-elements, one of the rotating S-elements has an S-shaped cross section, the other of the rotating S-elements has a mirror image of the S-shape cross section. In the preferred embodiment,a new mailpiece to be stacked enters the stacker below the top curve of the S-shaped elements, and above the shelf-like center portion of the S-shaped elements. The imaged portion of the mailpiece (i.e., the top side) does not contact either the stack or the upper curved portion of the S-shaped elements while being moved into the stacker. Thus, the likelihood of smearing is greatly reduced. Once the new mailpiece is moved into the area below the stack and between the two rotating S-shaped elements, the two elements are rotated 180 degrees. This action lifts the new mailpiece upward directly into contact with the bottom of the stack, thus lifting the entire stack by the thickness of the new mailpiece. Once again, during this lifting action, sliding motion does not occur or is minimized between the top side of the mail piece and the stack or the rotating elements. Smearing of the images such as address and indicia images is minimized or does not occur. Additionally, the weight of the stack is felt by the new mailpiece when it is in place in the stack; this improves sealing.
An advantage of the present invention is that it decreases image smearing, reduces stacker footprint, improves sealing, and provides ordered stacking (i.e., stacks in 1 to N order) which simplifies software requirements especially relating to jam recovery algorithms. For copiers and printers where page sequence is printed in forward order (1 to N) the pages or mailpieces can be stacked in correct order in the face up bottom stacker of the present invention. The apparatus also enables simple stack unloading while running. The stack unloading requires decreased operator skill. The apparatus is also cost effective. Other advantages of the invention will in part be obvious and will in part be apparent from the specification. The aforementioned advantages are illustrative of the advantages of the present invention.